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Science notes that Europe is often thought of as the "ancestral home of white people." But a new DNA study suggests that pale skin and other traits we associate with the continent may have emerged only within the last 8,000 years—a "relatively recent" occurrence. The study—published last month on the bioRxiv.com server and presented last week at the American Association of Physical Anthropologists' annual meeting—compared genome DNA across three populations of farmers and hunter-gatherers who crossed over into Europe in discrete migrations within the past eight millennia, Science notes. What scientists found: a handful of genes tied to diet and skin pigmentation that withstood natural selection and thrived in the northern regions. The data indicates hunter-gatherers who settled in Spain, Hungary, and Luxembourg about 8,500 years ago lacked two specific genes—SLC24A5 and SLC45A2—and had darker skin, Science notes.

But hunter-gatherers hunkered down further north in Sweden had both those light-skin genes and also a third gene that leads to blue eyes (and possibly fair skin and blond hair). When the third demographic, the Near East farmers, arrived, they also carried the SLC24A5 and SLC45A2 genes, so paler skin started emerging throughout the continent as the populations interbred. Although researchers don't offer a definitive answer as to why natural selection picked those genes to thrive in the north, one paleoanthropologist speculated at the meeting that the lack of sun in the northern parts of Europe required people to adapt by developing lighter skin to better absorb more vitamin D, as well as the LCT gene that allowed them to digest the sugars their ancestors couldn't in milk, also filled with vitamin D. (This one infant could tell us where the first Americans came from.)

https://youtu.be/PzEFDDZxnRE I just can't get over this. 8,000 years is the blink of an eye. The link is to a funny little youtube video with outrageous background music. It's supposedly about the genetic history of humans and their migrations in Europe 8,000 years ago. I can't vouch for its scientific accuracy, but it's entertaining.